| 摘要 |
PURPOSE:To detect only frost by detecting output fluctuation from a coil for elastic wave detection based upon characteristic mechanical convergence operation which is caused cyclically when frost is brought into contact with an elastic wave propagation body. CONSTITUTION:A frosting detector which is constituted by providing a coil 8 for elastic wave excitation to one end side of the elastic wave propagation body 3 and an elastic wave detection coil 8 to the other end side detects the output of the coil 9 for elastic wave detection by a detecting means 21 and recognizes the representative value of the detected output by a 1st recognizing means 22. The recognized representative value of the output is compared by a 1st comparing means 24 with a set value. Further, a 2nd recognizing means 24 recognizes the fluctuation width of the output detected by a detecting means 21 and a 2nd comparing means 25 compares the recognized output fluctuation width with set variation width. Then an output control means 26 outputs a defrosting signal according to the output results of the 1st and 2nd comparing means 23 and 25.
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